cleveland and that incredible story and new questions about how the three girls were held for so long. One of them for 11 years in that tiny house in that neighborhood. Abc anchor david muir has been looking at that. Why didn't they leave earlier? Reporter: Yes, so many asking that, elizabeth. You know, I spent some time with the fbi who told me about the extraordinary bond these women created inside the house, really part of their survival fear driving so much of what played out over those ten years which might explain why ammanda took that long to decide to pound on the door, pick up that fine and dial 911. AMANDA BERRY, gina DeJesus, michele knight, all held captive for a decade and more details are revealed and one question on the miefrndzs of so many, over the last ten years never another chance to escape? The fear of what if I tried to escape, I'm not successful then I'm killed many times will drive victims not to ait e. To escape. Reporter: What happened to shawn hornbeck. She was kidnapped by michael devlin. When he tried to strangle the boy, promised never to escape or tell the truth. He kept a word. Not a move for four years until police discovered him. He felt somewhat guilty he could kochts get away. I told him everything he did was right. Jaycee dugard was held 18 years telling diane her captor's grip was so strong she never tried to flee. My manipulation plus the physical abuse I suffered in the beginning, there was no leaving. Reporter: Dugard told diane she felt guilty for bonding with garrido. The abductor will be their own connection to the outside world and they may even on some levels look forward to seeing them. Your whole world is crashing down around you. Reporter: Elizabeth smarts with held by brian david mitchell and was too afraid to attempt to escape. They don't don't have a life experience to counter what the bad guy is telling them. Reporter: In this indicate, those will created a sort of family of their own inside that house and in the hours afterwards, they were asked can you check on each other going into each other's rooms and in fact some of the young women had the artwork of their little girl but proud to show it off when the police officers decided to check on them thflselves. They'll be a unit together for many years to come. Dr. Michael welner, you examined elizabeth smart's kidnappers and know what goes on in the minds of these kidnappers, describe this process of a traumatic bonding that holds the two together. Well, I think it's best for us to take a step back about these kinds ofituations and it's best to understand that the common modus operandi of a kidnapper or kidnappers is certainly to create an extraordinary amount of fear that they have a capacity either to kill the fact, the abduct ee or to kill their family. He will do a variety of things, physically, sexually to dehumanize the victim and it's the dehumanization which is the beginning of the process where the person loses their identity. What is part and parcel people have been away for a long time is that the kidnapper is invested and investigated their sense of who they were, their connection to their past which makes it easier to manipulate a continued connection. Part of that is making them entirely dependent upon the captor for their needs and i would also add when you have multiple people involved, not only captors, but captives, the prime move creates a system in which pima nip late each other. I wouldn't be surprised if the child was part of that. A threat to a helpless used to leverage continued compliance, so it's fear and dehumanization to elicit compliance, absolute lines which means absolute silence and the dependence and continued fear moves that along. It happens - it happens in a system involves a variety of people when they're available. If this system is working inside the house it doesn't surprise you that none of the neighbors with a couple of brief exceptions really saw anything or had any clues for so many years. It doesn't surprise me and important lesson to the general public because consider if someone is manipulative enough in his sexual deviance and ma nip tiff enough to come up with a system to inspire fear, dependence and absolute compliance, fooling and manipulating ignorant neighbors is easy, easy to understand how brian david mitchell was looking right at a police officer and elizabeth smart was right there in a library and the police officer says, are you elizabeth smart and she remains silent and brian david mitchell says you can't lift that veil because we're muslim so that kind of a manipulation is part of this and enables it. We don't have a lot of time. What does the fbi do now talking to the women to get the best information without making them relive this tumatic experience? It's very difficult and painful for the victims and there's no way around it. It may be that the youngest child may have had a protected experience, perhaps her experience was a little easier but there's no easier way around it. I would encourage you and your victims, many who have been victimized enduring the trauma is a tremendous service to other victims to be able to come forward and prevent other people from victimizing heres. You must be heard. The trauma will empower you to engage it and endure the short taif term pain and assist law enforcement and lock people up and you will make sure they will never hurt others again and discourage others from following this their footsteps knowing that eventual they'll be caught and the victim will heard. Will speak and not be silenced. Thanks for that. The weather for sam.

This transcript has been automatically generated and may not be 100% accurate.

{"id":19132450,"title":"Fear Can Stop Kidnapping Victims From Escape Attempts","duration":"7:03","description":"A look at what drives victims of kidnapping to stay put and not attempt an escape.","url":"/GMA/video/amanda-berry-gina-dejesus-michele-knight-found-fear-19132450","section":"GMA","mediaType":"Default"}